Civil Engineering All Engineering Career

The correct answer is "north to south."

The lines of the Earth's magnetic field run from the magnetic south pole to the magnetic north pole.

The correct answer is "horizontal and vertical angles."

A theodolite is an instrument used for measuring both horizontal and vertical angles with high precision.

front of the eye piece

The correct answer is "the objective should be focussed."

When the image formed by the objective is not situated in the plane of cross-hairs, you need to focus the objective to ensure that the image and cross-hairs are properly aligned. This adjustment ensures accurate measurements and observations through the telescope.

The correct answer is "both (a) and (b)."

To remove parallax, you should:

• Focus the eyepiece for a distinct vision of the cross-hairs (to ensure the cross-hairs are clearly visible).
• Bring the image of the object into the plane of the cross-hairs (to align the object image with the cross-hairs).

Both adjustments are necessary to eliminate parallax and ensure accurate measurements.

The correct answer is "1 cm = 25 m."

In a representative fraction (RF) of 1/2500, the scale means that 1 unit on the map (or drawing) represents 2500 of the same units in reality. Therefore, 1 cm on the map represents 2500 cm in reality. Converting 2500 cm to meters gives 25 meters.

The correct answer is "magnification."

The magnification of a telescope is determined by the ratio of the focal length of the objective lens to the focal length of the eyepiece. It indicates how many times larger an object appears through the telescope compared to the naked eye.

direct angle

The correct answer is "higher than."

If a chain is used at a temperature higher than the temperature at which it was calibrated, the chain expands due to thermal effects, resulting in a longer length than originally measured. This causes the measured length to be greater than the actual length, resulting in a negative error in the measured length.

The correct answer is "river."

A river is an obstacle that obstructs chaining (the physical measurement of distance) but not vision, as you can still see across it but cannot easily measure the distance directly across.